1. Field of the Invention
The present invention relates to an optical sensor module including an optical waveguide unit, and a substrate unit with an optical element mounted therein.
2. Description of the Related Art
As shown in FIGS. 9A and 9B, an optical sensor module is manufactured by: individually producing an optical waveguide unit W0 in which an under cladding layer 71, a core 72 and an over cladding layer 73 are disposed in the order named, and a substrate unit E0 in which an optical element 82 is mounted on a substrate 81; and then connecting the substrate unit E0 to an end portion of the optical waveguide unit W0 with an adhesive and the like, with the core 72 of the optical waveguide unit W0 and the optical element 82 of the substrate unit E0 kept in alignment with each other. In FIGS. 9A and 9B, the reference numeral 75 designates a base, and 85 designates a sealing resin.
The alignment between the core 72 of the optical waveguide unit W0 and the optical element 82 of the substrate unit E0 is generally performed by using a self-aligning machine, as disclosed in, for example, Japanese Published Patent Application No. 5-196831 (1993). In this self-aligning machine, the alignment is performed, with the optical waveguide unit W0 fixed on a fixed stage (not shown) and the substrate unit E0 fixed on a movable stage (not shown). Specifically, when the optical element 82 is a light-emitting element, the alignment is performed in a manner to be described below. As shown in FIG. 9A, light H1 is emitted from the light-emitting element. In this state, while the position of the substrate unit E0 is changed relative to a first end surface (light entrance) 72a of the core 72, the amount of light emitted outwardly from a second end surface (light exit) 72b of the core 72 through a lens portion 73b provided in a front end portion of the over cladding layer 73 (the voltage developed across a light-receiving element 91 provided in the self-aligning machine) is monitored. Then, the position in which the amount of light reaches a maximum value is determined as an alignment position (a position in which the core 72 and the optical element 82 are appropriate relative to each other). On the other hand, when the optical element 82 is a light-receiving element, the alignment is performed in a manner to be described below. As shown in FIG. 9B, the second end surface 72b of the core 72 receives a constant amount of light H2 (light emitted from a light-emitting element 92 provided in the self-aligning machine and transmitted through the lens portion 73b provided in the front end portion of the over cladding layer 73). The light H2 is emitted outwardly from the first end surface 72a of the core 72 through a rear end portion 73a of the over cladding layer 73. In this state, while the position of the substrate unit E0 is changed relative to the first end surface 72a of the core 72, the amount of light received by the light-receiving element (the voltage) is monitored. Then, the position in which the amount of light reaches a maximum value is determined as the alignment position.
However, the alignment using the above-mentioned self-aligning machine can be high-precision alignment, but requires labor and time and is therefore unsuited for mass production.
An optical sensor module capable of achieving alignment without such equipment and labor as mentioned above is disclosed in Japanese Patent Application No. 2009-180723. FIG. 10A is a plan view of this optical sensor module, and FIG. 10B is a perspective view of a right-hand end portion of the optical sensor module as seen diagonally from the upper right. With reference to FIGS. 10A and 10B, this optical sensor module includes an optical waveguide unit W1 having extensions 44 configured such that opposite end portions of an under cladding layer 41 and an over cladding layer 43 where a core 42 is absent (upper and lower portions thereof at its right-hand end as seen in FIG. 10A) are extended in an axial direction. The extensions 44 include a pair of vertical groove portions (fitting portions) 44a extending across the thickness of the optical waveguide unit W1 and for fitting engagement with a substrate unit. The extensions 44 are provided in an appropriate position relative to a light-transmissive surface (a first end surface) 42a of the core 42. The optical sensor module further includes a substrate unit E1 having fitting plate portions (to-be-fitted portions) 51a for fitting engagement with the respective vertical groove portions 44a. The fitting plate portions 51a are provided in an appropriate position relative to an optical element 54, and protrude along the width of the substrate unit E1 (leftwardly and rightwardly as seen in FIG. 10B).
In the optical sensor module, the fitting plate portions 51a provided in the substrate unit E1 are brought into fitting engagement with the respective vertical groove portions 44a provided in the optical waveguide unit W1. In this state, the optical waveguide unit W1 and the substrate unit E1 are coupled to each other in the optical sensor module. The vertical groove portions 44a are in an appropriate position relative to the light-transmissive surface 42a of the core 42, and the fitting plate portions 51a are in an appropriate position relative to the optical element 54. Thus, the fitting engagement between the vertical groove portions 44a and the fitting plate portions 51a allows the core 42 and the optical element 54 to be automatically brought into alignment with each other. In FIGS. 10A and 10B, the reference numeral 45 designates a base, the reference character 45a designates a through hole formed in the base 45 and for insertion of the substrate unit E1 therethrough, 51 designates a shaped substrate provided with the fitting plate portions 51a, and 55 designates a sealing resin.